This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Hi dear people,
continuing with my project using the TLV320DAC3203, I have some questions related to MICBIAS settings:
On the TLV320DAC3203 Applications Reference Guide I can read the following:
Page 1 / Register 51: MICBIAS Configuration Register
BIT READ/WRITE RESETVALUE DESCRIPTION
D7 R 0 Reserved. Write only default value.
D6 R/W 0 0: MICBIAS powered down
1: MICBIAS powered up
D5-D4 R/W 00 MICBIAS Output Voltage Configuration
00: MICBIAS = 1.04V (CM=0.75V) or MICBIAS = 1.25V(CM=0.9V)
01: MICBIAS = 1.425V(CM=0.75V) or MICBIAS = 1.7V(CM=0.9V)
10: MICBIAS = 2.075V(CM=0.75V) or MICBIAS = 2.5V(CM=0.9V)
11: MICBIAS is switch to power suppl
D3 R/W 0 0: MICBIAS voltage is generated from AVDD
1: MICBIAS voltage is generated from LDOIN
D2-D0 R 000 Reserved. Write only default value
However, the GUI of the EVM sets D3 to 1 when I select AVDD as source for MICBIAS
Question 1: Which one is the good setting? Is the information on the data sheet wrong?
The other questions are related to Table 2-12 on P. 33 of the Reference Guide, for the MICBIAS Voltage Control:
here not only Page 1 Reg 51 is being used, but also Page 1 Reg 10 (Common Mode Control Register)
I can also read on pages 34 and 48:
"The common-mode voltage setting of the device is determined by the available analog power supply.
This common-mode (input common-mode) value is common across the ADC, DAC and analog bypass path.
The output common-mode setting is determined by the available analog power supplies (AVDD and ) and
the desired output-signal swing."
However, I can not really understand how to apply this.
In my setting, I have two dig mics from Knowles with PDM Output accepting up to 3.6V Supply Voltage, while typical would be 1.8V, being 1.6V the MIn.
My intention is (or was), to feed the mics with MICBIAS, hoping for a better Noise-Signal ratio.
The EVM is working with 3.3V. This is ok for my testing.
For my final setting, with my own hardware, I need everything to work with 2V (I had planned to use 1.8V, but the MCU won't start, so I made a compromise)
The DAC3203 is becomming those 2V on AVDD, DVDD, IOVDD and LDOIN
The output of the DAC goes to HPL and HPR
Question 2: Would you advice to feed the mics directly with the VDD Power of the system, instead of going via MICBIAS, or can I use MICBIAS to lower the Supply for the mics?
Question 3: What would be the difference regarding noise, for instance, for the TLV320DAC3203 to work with, since the digital signal of the mics would be lower as the Supply?
Thanks in advance for your help!
Best regards,
Gustavo
Hi Gustavo,
I'll check on your questions and provide some answers by tomorrow morning.
Best regards,
-Ivan Salazar
Applications Engineer
Hi Gustavo,
Adding comments on each question below:
Best regards,
-Ivan Salazar
Applications Engineer
Hi Ivan,
you have answered my questions, thanks!
And no, there is no reason to have a different voltage level for the mics. I was not sure about setting the MICBIAS = LDOIN. Now is clear.
Best regards,
Gustavo